CLN: Clean up imports.  Use absolute imports.
CLN: Lazy imports of matplotlib and descartes
TST: Remove matplotlib and descartes from requirements.txt (at least until there are plotting tests)
TST: Run Travis CI tests on 2.6 as well
Revert "TST: Run Travis CI tests on 2.6 as well"

This reverts commit dbbc9faefca88d739522e298e493d70f3ea5b406.
Merge pull request #31 from kjordahl/cleanup/imports

Clean up imports
TST: Run Travis CI tests on both release and master versions of pandas
TST: Environment variable in .travis.yml needs to be preceeded by dollar sign
TST: Add Cython to requirements (needed to build pandas)
TST: Try direct install of pandas in .travis.yml
BUG: Use generic **kwargs to catch changes in pandas method APIs
Merge pull request #32 from kjordahl/feature/travis-pandas-versions

Run Travis CI tests on multiple pandas versions
CLN: Remove unused internal function
CLN: Remove useless test
TST: Add a test for GeoSeries to/from file
TST: Add tests for 'not in' GeoSeries
TST: Use unittest assertion methods
TST: add missing assertions
TST: Explicit skips of not yet implemented tests
TST: Assertions for expected exceptions